I'm two months into a 6 month goal that honestly just no longer excites me.
My experience tells me that is always better to cut losses early than hang on to the potential that this product will become more interesting to me.
The truth is that the problems I'm working on today should excite me, but don't, and I know that as more users depend on this product, it will become more difficult to shut down in the future.
Fret not, though! Saying no to this product means that I can say yes to other products that I'm obsessed about working on - they are intrinsically motivating.